Royal Prussian Jagdstaffel 66, commonly abbreviated to Jasta 66, was a "hunting group" (i.e., fighter squadron) of the Luftstreitkräfte, the air arm of the Imperial German Army during World War I. The squadron would score over 97 aerial victories during the war, including seven observation balloons downed. The unit's victories came at the expense of five pilots killed in action, one who died in captivity, and two taken prisoner of war.